Two bodies at different temperatures `T_(1) and T_(2)`, if brought in thermal contact do not necessarily settle to the mean temperature `(T_(1)-T_(2))//2`. Why ?

Explanation

If the two bodies are of the same substance then the heat lost by a hot body is equal to the heat gained by a cold body .i.e., `m_(1)(theta_(1)-theta)= m_(2)(theta_(1)-theta_(2))` where `theta_(1) gt theta_(2) and .theta.` is the resultant temperature.
`i.e., theta=(mi_(1) theta_(1)+m_(2) theta_(2))/(m_(1)+m_(2))`
if `m_(i)=m_(2)` then `theta=(theta_(1)+theta_(2))/(2)` if `m_(1) ne m_(2)`, then `theta ne (theta_(1)+theta_(2))/(2)`